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Supernova shock wave creates halo effect

The shock wave from supernova 1987A heated gas around the dead star to millions of degrees, causing it to glow at X-ray wavelengths

(Image: NASA/CXC/PSU/S Park/D Burrows)

Optical hotspots glow pearly pink as the supernova’s shock wave slams into cool, dense fingers of gas on the edge of a cavity surrounding the exploded star

(Image: NASA/STScI/CfA/P Challis)

The shock wave from a bright supernova that exploded in 1987 has now reached the edge of a cavity around the dead star, reveal new observations with the Hubble Space Telescope and the Chandra X-ray Observatory.

As intense heat from the shock wave continues to spread, it will illuminate the dense gas blown off by the detonating star, which was originally about 20 times more massive than our Sun.

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Called 1987A, the supernova was the brightest recorded in 400 years and exploded in a nearby galaxy called the Large Magellanic Cloud. Astronomers believe that about a million years before the supernova, the star lost most of its outer layers through a slow-moving wind of particles.

Glowing donut

Then, before it blew up, it drove out a high-speed wind that carved a cavity almost devoid of matter around itself. Hubble glimpsed the edge of this cavity when the supernova lit up the region like a flashbulb in 1987. The explosion created a fast-moving shock wave that Chandra observed in 1999 as it travelled through the cavity.

Now, that shock wave appears to have reached the edge of the cavity and is heating the dense gas there to millions of degrees. The evidence comes from a ring of superheated gas detected by Chandra and pearl-like “optical hotspots” seen by Hubble. (View time-lapse Chandra images here, mov format.)

The hotspots are thought to have formed where the shock wave rammed into blobs of cool gas that had been whittled into finger shapes by the fast stellar wind that carved out the cavity. (View an animation here, mov format).

As the shock wave expands further into the dense cloud of gas and dust ejected by the first, slower wind a million years ago, it will reveal clues about the star that spawned the famous supernova. “Supernova 1987A will be illuminating its own past,” says Chandra team member Richard McCray.